In general, a parking mechanism of a transmission for a vehicle, in particular, a parking mechanism of a transmission which is actuated in conjunction with the operation of a manual shift lever is usually constructed as follows. A lever and detent mechanism is rotated by the operation of a manual shift lever so that the detent and shaft rotate integrally. The rear end of a rod to which is fitted a cam at the forward end thereof is linked with the above mentioned lever. And if the cam runs onto an inclined surface of a bracket which surface is projected forwards in the moving direction thereof, a pawl lever, with a pawl, mounted perpendicular to the bracket is pushed up thereby, so that the pawl of the pawl lever engages a parking gear which is drivingly or operatively coupled to an output shaft of the transmission, thereby locking the output shaft. Since the bracket and the rod with the cam are guided conventionally by the long rod which is projected towards the front area of the cam in the parking mechanism of the transmission of this type, there is caused a drawback in that the dimension in the axial direction becomes large. Since it is required to shorten the dimension in the axial direction of the transmission, in particular, in the case of the transverse setting of the engine as in the front wheel drive cars and the like, the parking mechanism of the transmission of the above mentioned type is improper.